I can think of a few myths/falsehoods:
You can't make a good quilt without a fancy/expensive sewing machine, a dedicated sewing room, and lots of specialized rulers.
Binding must be sewn by hand.
It's rude to let a dog sleep on a handmade quilt, or to use it as a picnic blanket.
A handmade quilt must be instantly cherished and loved by its recipient, or they are a Bad Person.
Pre-cuts are always the right size.